The Research On The 3D Real-time Rendering Optimized Base On GPU

Scientific visualization, computer 3-D (Three dimension) animation and virtual reality are the three major research direction in computer graphics recently, and the core technology is 3D realistic graphics. Current 3D real-time rendering technology is commonly applied in many fields including military, aerospace, aviation, medicine, geology, exploration,3D games and CAD (Computer-aided design) industry etc.CPU (Central Processing Unit) is a general purpose processor, which needs to consider the balance among the program execution, data parallel computing and universality, so most of the transistors in CPU are used for the large cache and complex logic control unit, but the occupation probability of operation unit is very small. Although multi-core CPU products appear, it doesn't improve the utilization of the transistor. At the same time, propelled by the game industry, GPU (Graphics Processing Unit) performance rate is doubled per year. In order to achieve more realistic graphics effect, more and more complex operations are supported by CPU. The single-precision floating-point operations of the mainstream GPU can reach about ten times performance of CPU in the same period, and the external memory bandwidth is about five times the CPU. GPU computing architecture beats the CPU in the cost and power consumption. As CUDA comes out, it overcomes many difficulties that the traditional GPU-based ray tracing algorithms encountered.This dissertation gives a detailed analysis on 3-D real-time rendering optimization based on GPU and also proposes some effective solutions and suggestions. The main research includes:3-D real-time rendering GPU pipeline optimization methods and parallel computing performance optimization methods; the traditional shadows algorithm; the pluses and minuses of rasteration.The main work and contributions of this dissertation are listed as following:Firstly, a technical framework of GPU and its graphics rendering pipeline are introduced, which includes super pipelines, parallel computing, vertex processor, and fragment processors. For the difference between GPU and CPU, the acceleration principles of GPU are analyzed; and the general-purpose computing model of current mature framework CUDA and its characteristics are discussed. Secondly, parallel computing and rendering pipeline in 3-D real-time rendering optimization are studied. For the rendering pipeline, all the bottleneck stages that often occur in pipelines are analyzed and the optimization methods for all the stages are put forward accordingly. In parallel computing, the optimization goal is to complete the calculation within the allowable error in the shortest time, therefore, calculation density and throughput become the key points, and three parallel computing optimize principles which lay a solid theoretical foundation for 3-D real-time rendering system are summarized in the CUDA architecture.Thirdly, the concept and classification of shadow are introduced, then the strategies of traditional rasterization-based shadow rendering are analyzed and the deficiencies of a variety of shadow algorithms are summarized. Rendering using ray tracing method can reflect the real world, however, the drawback is that the computation is very huge and computing processing is quite long. Therefore, we propose a GPU-based parallel PKD-Tree can be constructed 3-D scene on the division algorithm to detect objects in the scene light and intersection of the situation and demonstrate real-time shadows, and make comparison with the traditional KD-Tree.For the 3-D real-time rendering bottleneck - graphics generation rate, a GPU-based 3-D real-time rendering system is implemented. The system is based on current graphics hardware and software architecture, in particular the graphics capabilities of the hardware accelerator and the graphics are generated by the variety of acceleration. In addition, according to the organizational structure of the virtual scene and graphics realistic levels, the PKD-Tree traversal methods and second light treatment methods are analyzed, after that, the results of realistic light effect using recursively rendering are realized.Eventually, research trends of 3-D real time rendering technology are discussed.